import java.util.LinkedList;
import java.util.Queue;

public class MyStackusequeue {
    public Queue<Integer> queue1;
    public Queue<Integer> queue2;


        public MyStackusequeue() {
            queue1 = new LinkedList<>();
            queue2 = new LinkedList<>();
        }

        public void push(int x) {
            if(!queue1.isEmpty()){
                queue1.offer(x);
            }else if(!queue2.isEmpty()){
                queue2.offer(x);
            }else
                queue1.offer(x);
        }

        public int pop() {
            if(empty()){
                return -1;
            }if(!queue1.isEmpty()) {
                int len = queue1.size();
                for (int i = 0; i < len-1; i++) {
                    queue2 .offer(queue1.poll()) ;
                }
                return queue1.poll();
            }else  {
                int len = queue2.size();
                for(int i = 0;i < len-1;i++) {
                    queue1.offer( queue2.poll());
                }
                return queue2.poll();
            }
        }

    public int top() {
        if(empty()) {
            return -1;
        }
        if(!queue1.isEmpty()) {
            int size = queue1.size();
            int val = 0;
            for(int i = 0;i < size;i++) {
                val = queue1.poll();
                queue2.offer(val);
            }
            return val;
        }else  {
            int size = queue2.size();
            int val = 0;
            for(int i = 0;i < size;i++) {
                val = queue2.poll();
                queue1.offer(val);
            }
            return val;
        }
    }

        public boolean empty() {
            return queue1.isEmpty()&&queue2.isEmpty();
        }
    }

